Premature rupture of the amniotic sac is a common disorder that happens to occur in around 10% of pregnant women. Failure to treat premature rapture may cause intra-amnion infection, disruption in fetal lung development and even perinatal death.
Several approaches for detecting amniotic leakage are known in the art, including chromatographic detection of a color change in a diagnostic article following contact with vaginal secretion.
A number of devices involving panty shields, swabs and the like, with indicators aimed to identify amniotic fluid were developed, for example, in U.S. Pat. Nos. 5,897,834; 6,126,597 and 6,149,590. These devices can be worn, or otherwise used, by the user and whenever there is a secretion it is absorbed and further detected.
U.S. Pat. No. 6,921,647 and Continuation-in-Parts thereof, including, U.S. Pat. Nos. 7,314,752; 7,541,177 and 7,947,467 disclose secretion-monitoring article for identifying a secreted biological fluid, including, amniotic fluid, comprising: a body that includes an absorbent material and an indicator system having at least one pH determining member. The pH determining member includes a chemical composition which reacts with fluids containing urea differently than with fluids that do not contain urea, in a manner such that the former can be distinguished from the latter while avoiding false positive indications. The pH determining member may further, or alternatively, include a hydrophobic chemical composition that reacts with fluids based on the buffer capacity thereof, such that fluids having different buffer capacities can be distinguished.
It has been also proposed to detect the rupture of the amniotic sac by employing immunochemical analysis of the proteins in the amniotic fluid, such as, alpha-fetoprotein, prolactin, fibronectin, and insulin-like growth-factor binding protein 1. For example, U.S. Pat. No. 8,114,610 discloses a method of detecting amniotic fluid in a sample comprising a vaginal secretion of a pregnant woman using a combination of PAMG-1-specific monoclonal antibodies.
There is an unmet need for an improved diagnostic system that can differentiate between amniotic fluid and an interfering biological fluid, such as, urine, with minimal false positive results, while providing a reliable indication which is stable over time, and while reducing the amount of time required to get the reliable result.